Dereferring nullpointer in s1251

[christiana]

In s1251 here, s1710 is called. the return value jstat can be 5:

parameter value at end of
curve, rcnew1=SISL_NULL or
rcnew2=SISL_NULL.

indicating that qc1 OR qc2 may be NULL. This is not handled by s1251, leading to a nullptr exception here or here in our case.

Our analysis is that in this case we are approaching the resolution limit, but the check for this in s1251 is slightly different from that in s1710. It might be solved by checking for NULL and stop recursion.